Эрдэмтэд Италийн нутаг дэвсгэрээс олдсон 130 сая жилийн настай чулуулгийн ул мөрийг судалснаар гүн тэнгисийн сээр нуруутан амьтдын амьдралын талаарх ойлголтыг өөрчиллөө.
Италийн Хойд Апенниний уулсаас олдсон дөрвөн сантиметр орчим өргөнтэй нүхнүүд болон тахир муруй мөрүүд нь эртний загас өнөөгийн гүн тэнгисийн экосистемтэй адил аргаар хооллож байсныг гэрчилж байна. Палеонтологич Андреа Баукон болон түүний багийнхны Proceedings of the National Academy of Sciences сэтгүүлд нийтэлсэн судалгаагаар, эдгээр ул мөр нь загас гүн тэнгисийн орчинд амьдарч байсныг өмнөх судалгаануудаас 80 сая жилийн өмнө буюу Эртний Цэрдийн галавын үед тогтоожээ.
Судлаачид эдгээр олдворыг тайлахын тулд Номхон далайн Кермадек хотгорт амьдардаг “сүнс загас” буюу химера загасны хооллох зан үйлийг ажигласан байна. Орчин үеийн гүн тэнгисийн загаснууд лаг шавар дотроос идэш тэжээлээ хайхдаа ижил төстэй нүх, мөр үлдээдэг болохыг тэд тогтоожээ. Эртний Тетис далайн ёроолд органик бодисын нөөц ихэссэн нь ёроолын өт хорхой олшроход нөлөөлж, улмаар загаснууд гүн тэнгисийн харанхуй, хүйтэн орчинд хоол тэжээл хайн нүүдэллэх болсон гэж эрдэмтэд тайлбарлав.
Энэхүү нээлт нь дэлхийн түүхэн дэх амьдралын хөгжлийн үл мэдэгдэх нэгэн бүлгийг тодруулж буй чухал ач холбогдолтой юм. Судалгаанд оролцсон Карлос Нето де Карвальо болон Марио Качао нарын үзэж буйгаар, сээр нуруутан амьтдын идэвхтэй үйл ажиллагааг хадгалсан ийм чулуулгийн олдвор нь маш ховор тохиолддог байна.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
A few strange pits and trails preserved in ancient Italian rocks have changed what scientists thought they knew about the earliest vertebrate fossils from the deep ocean. Dating back 130 million years, these fossil traces show that fish were exploring the deep sea 80 million years earlier than the previous fossil record suggested.
Before this discovery, the oldest known fossil evidence of deep-sea fish was just 50 million years old. The new find takes that story much further back, to the Early Cretaceous, when dinosaurs still roamed the land and fish were already feeding on a muddy seafloor thousands of meters below the ocean’s surface.
The fossils were discovered in the Northern Apennines, near Piacenza, Modena and Livorno in Italy. According to the Faculty of Sciences of the University of Lisbon, the international team behind the discovery published its findings in the Proceedings of the National Academy of Sciences.
Strange Marks in the Rocks Revealed Something Unexpected
At first glance, the fossils may not look spectacular. There are no complete skeletons, sharp teeth or perfectly preserved fish. Instead, scientists found bowl-shaped pits and a winding trail left behind in ancient mud.
But these marks tell a remarkable story. The pits, some about four centimeters wide, were created by fish digging into the seafloor while looking for food. The winding trail was apparently made by the tail of a swimming fish brushing against the muddy bottom.
“When I first found the fossils, I could not believe what I was seeing,” said Andrea Baucon, the paleontologist who led the study and discovered the traces.
His surprise came down to one thing: their age. At 130 million years old, the fossils predate every other known piece of evidence for deep-sea fish by tens of millions of years.
“The new fossils show the activity of fishes on a dinosaur-age seafloor that was thousands of meters deep,” Baucon added.
Ghost Sharks Helped Unlock an Ancient Mystery
Figuring out what made these ancient marks wasn’t simply a matter of looking at the rocks. The researchers turned to living fish for clues. They studied chimaeras, often called ghost sharks, in modern deep-sea environments. One was observed at the Kermadec Trench in the Pacific Ocean, swimming above the sediment at a depth of 1,544 meters before plunging its mouth into the seabed to feed.
Modern fish can use suction to uncover prey buried in sediment. Others scratch the seafloor while searching for something to eat. These behaviors leave behind structures identical to the ones found in the Cretaceous rocks of the Northern Apennines.
Fossil pits and trails reveal ancient fish activity on a 130-million-year-old deep seafloor. Credit: PNAS
The ancient traces are also reminiscent of feeding behaviors associated with Neoteleostei, a group that includes modern jellynose fishes and lizard fishes.
The study co-author Mário Cachão explained that the deep-sea sediments often contain fossils of small organisms that once lived higher in the water column, including phytoplankton and zooplankton. Finding direct signs of vertebrate activity preserved in these rocks is a very different story, and an extremely rare one.
Ancient Fish Followed Food Into the Deep
So why did fish leave shallower waters and venture into a world of total darkness, near-freezing temperatures and enormous pressure? As explained in the latest research, the study team points to food as the answer.
The study authors said that an unprecedented influx of organic matter reached the deep ocean between the Late Jurassic and Early Cretaceous. This abundance of food allowed bottom-dwelling worms to thrive, which, in turn, attracted fish capable of digging into the sediment or using suction to extract their prey.
All of this happened beneath the Tethys Ocean, an ancient ocean that existed between 250 million and 50 million years ago and preceded today’s Mediterranean Sea.
The sediments preserving these traces had quite a journey of their own. They were eventually tectonically deformed and exposed as part of the Northern Apennine mountain range, mainly during the Miocene and Pliocene epochs.
“The new fossils shed light on an otherwise obscure chapter of the history of life on Earth,” said Carlos Neto de Carvalho, a researcher involved in the study.
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